[Adsorption of neutral polymers on liposomes: investigation of the correlation between liposomes and polymers]

The characteristics of the adsorption process of neutral polymers: poly(vinyl alcohol), poly(vinyl pyrrolidone), and dextrane onto liposomes with three different lipid compositions were investigated as follows. 1 determination of the amount of polymers adsorbed on the surface of liposomes, 2 detection of the changes in the membrane structure brought by the adsorption of polymers with a high precision densimeter, 3 test dye release experiments with membrane diffusion cells after remote loading of liposomes with acridine orange (AO). The amount of polymers adsorbed on the surface of liposomes was expressed with adsorption isotherms at 25 +/- 1 degrees C. Connections were found between the lipid composition influencing the fluidity of liposome membrane, the surface charge density of liposomes, the physical-chemical properties of the polymers and the quantitative adsorption properties of the polymers. Decreasing of the molar excess volume values counted from the results of the high precision densimetric measurements revealed the compression of the membrane structure caused by polymer adsorption. We were able to influence the test dye (AO) release properties of the soy lecithin phospholipid (SLPL)/cholesterol (Chol)/dicethyl phosphate (DCP) = 25:3:2 (mol/mol) liposomes by the changing of the amount of PVA or DEX added to their dispersions.